Door safety latch

ABSTRACT

A door safety latch permitting the partial opening of a door consisting of an arcuate lug mounted on the door, and having an enlarged ball portion mounted on the end thereof, with a fastening member mounted in the door frame having a pivoted yoke portion whose spaced apart leg portions prevent the ball portion of the lug from passing therethrough. At the pivoted end of the yoke portion, the leg portions are sufficiently spaced apart to permit the ball portion to pass therethrough. When the door is in a closed position and the safety latch swung to the position to permit only a partial opening of the door, the arcuate lug will extend through the space between the leg portions. In order to prevent the pivoting of the yoke by a person on the outside of the door, as by a burglar, means are provided offering frictional resistance to the turning movement of the yoke so that he is unable to cause the yoke to swing from its door locking position to the position that permits the door to open to its completely open position.

BACKGROUND OF THE INVENTION

1. Field of The Invention

This invention relates to door locking devices and is more particularlydirected to a safety latch that permits only a partial opening of adoor.

2. Description Of The Prior Art

There are presently two types of door safety latches that permit thepartial opening of a door so that a person within the dwelling can seewho is at the door. Both types operate on the same principle except thatone type uses a slide member on the end of a chain while the other usesa pivoted yoke. It has been discovered that these door safety latchescan be manipulated by a person such as a burglar from the outside of thedoor so that a latch that was positioned to permit only the partialopening of a door can be manipulated to permit the total opening of thedoor. This is accomplished by the use of a rubber band which is securedat one end by a thumb tack in an appropriate position on the walladjacent to the door and the other end under tension to the slide memberor to the free end of the yoke with the door only partially opened. Nowwhen the door is closed, the tension of the rubber band will cause theslide member or the yoke to move to the position which causes the safetylatch to permit the door to open to its completely open position. Thisthereby renders the safety latch unable to perform the purpose intended,namely, to permit the door to be opened only partially for the purposeof recognizing the person wishing to pass through the door. The presentinvention contemplates preventing a person from being able to manipulatea door safety latch from the outside of the door.

Summary Of The Invention

Therefore a principle object of the present invention is to provide asafety door latch that permits only the partial opening of a door frombeing manipulated by a person outside the door.

A further object of the present invention is to provide a safety doorlatch with a lug that is mounted on a door and a pivoted yoke mounted ona door frame that engages the lug to permit the door to be onlypartially opened and which yoke cannot be manipulated from the outsidewhen the latter is positioned for permitting the partial opening of thedoor.

A still further object of the present invention is to provide a safetydoor latch for the partial opening of a door with a pivoted yoke thatengages a detent thereby preventing the manipulation of the yoke fromthe outside of the door.

With these and other objects in view, the invention will be bestunderstood from a consideration of the following detailed descriptiontaken in connection with the accompanying drawing forming a part of thisspecification, with the understanding, however, that the invention isnot confined to any strict conformity with the showing of the drawingbut may be changed or modified so long as such changes or modificationsmark no material departure from the salient features of the invention asexpressed in the appended claims.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing:

FIG. 1 is a perspective view of a wall including a door upon which mydoor safety latch is mounted.

FIG. 2 is a similar but enlarged view of my door safety latch with thelatter in position to permit the opening of the door to its completelyopened position.

FIG. 3 is a similar view with latch in position to permit only a partialopening of the door.

FIG. 4 is a similar view showing the door in its partial openedpositioned.

FIG. 5 is a cross sectional view taken along the line 5--5 of FIG. 3.

FIG. 6 is a side elevational view of my plastic detent.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawing wherein like numerals are used to designatesimilar parts throughout the several views, the numeral 10 refers to adoor safety latch constructed in accordance with my invention and shownmounted in position on a door 11 hinged to a door frame 12 on a wall 13at an opening 14. Like all door safety latches that permit a partialopening of the door, the device 10 is mounted on the door 11 and doorframe 12 in proximity of the door knob 15. The door safety latch 10consists of a keeper --K-- mounted on the door 11 and a fastener --F--mounted on the door frame 12.

The keeper --K-- which consists of a flat base member 20 is secured tothe door 11 by screws 21. A lug 22 extends angularly and outwardly ofthe base member 20 in the direction of the fastener --F-- terminating ina spherical member or ball 23 having a diameter greater than the widthof the lug 21.

The fastener --F-- which is mounted on the door frame 12 adjacent to thekeeper --K-- is provided with a flat base member 25 that is fastened byscrews 26 to the door frame 12. Mounted on the base member 25 is a pairof lugs 27 and 28 extending outwardly thereof in spaced relation to eachother. The free ends of the lugs 27 and 28 are each provided with apivot pin 29 for pivotally mounting a yoke --y-- thereon. The yoke --y--consists of a pair of leg portions 30 joined at their free end as at 31and extend in parallel relation for a portion of the distance toward thelugs 27 and 28 at which position 32 the leg portion 30 extend in adirection away from each other to increase the space between the legs 30for the remainder of the distance to the lugs 27, 28 where the pivotpins 29 pivotally secure the yoke --y-- to the lugs 27 and 28. The spacebetween the leg portions 30 of the yoke --y-- that extend to the freeend 31 from the bent portions 32 is equal to width of the lug 22 of thekeeper --K-- and permits the lug 22 to slide along the yoke --y--. Theball 23 prevents the keeper --K-- from becoming separated from thefastener --F-- as the lug 22 is in that portion of the yoke --y-- andthe door 11 can be only partially opened as shown by FIG. 4. However,the ball 23 is free to slide out from between the leg portions 30 whenthe ball 23 is positioned in that portion of the yoke --y-- that extendsfrom the bent portions 32 to the pivot pins 29. At this position, theball 23 of the keeper --K-- becomes separated from the fastener --F--and the door 11 can then be swung to its completely open position.

The fastener --F-- is provided with means to maintain the yoke --y-- ina locking position or in one of two opening positions consisting adetent --D-- mounted in a cavity 33 formed in the lug 28. The detent--D--, which is made of resilient plastic material, consists of a baseportion 34, a body portion 35 extending outwardly thereof. A headportion 36 is attached as at 37 to the body portion 35, the joiningmember 37 is of smaller diameter than that of the body member 35 or thehead member 36 to permit movement of the head member 36 as is explainedhereinafter. The head member 36 bears against inner arcuate end portion38 of one of the legs 30 of the yoke --y-- which portion 38 is providedwith three stepped surfaces 40, 41 and 42 disposed about arcuate endportion 38. The head portion 36 engages each of the stepped portions asthe yoke --y-- is swung from one extreme position, the non-lockingposition to the other extreme position, namely the locking position.

In the normal use of my door safety latch 10, when it is desired topermit only the partial opening of the door 11, the yoke --y-- is swungin the direction of the door 11. In this position the head 36 of thedetent --D-- will engage the stepped surface 40 and the lug 22 willextend between the leg portions 30 of the yoke --y-- as shown in FIG. 3and the solid lines of FIG. 5. Now, when the door 11 is swung to itsopen position, lug 22 along with the ball 23 will slide along andbetween the leg portions 30. Since the ball 23 is larger than the spacebetween the leg portion 30, the lug 22 will slide toward the end 31 ofthe yoke --y-- until the ball 23 engages the end portion 31 of the yoke--y-- to prevent any further opening of the door 11 as shown by FIG. 4.

If it is desired that the door 11 be permitted to swing to itscompletely open position, the yoke --y-- is then swung about its pivotpins 29 to cause the head 36 of the detent --D-- to engage either thestepped surface 41 or 42. In this position, the ball 23 of the keeper--K-- will be found between the leg portions 30 that extend from thebent portion 32 to the pivoted end portions. At this position, whereinthe space between the legs 30 is greater than the diameter of the ball23, the latter along with the keeper --K-- is free to move away from thefastener --F-- as the door 11 may be swung to its completely openposition.

The function of the detent --D-- and the stepped surfaces 40, 41 and 42on the yoke --y-- is to offer frictional resistance to the swingingmovement of yoke --y-- so that a person outside the door cannot swingthe yoke to the position that permits the opening of the door. Forexample, if the yoke --y-- swung easily, when the door is partiallyopened as shown by FIG. 4, a person can easily insert his hand throughthe opening. By use of a rubber band, which he fastens to the endportion 31 of the yoke --y-- and stretches the rubber band to fasten theother end to the wall 13 by a thumb tack so that when the door 11 is nowclosed, the tension of the rubber band will swing the yoke about thepivot pins 29 in the direction of the wall 13 to the position shown byFIG. 2. The door 11 can now be opened to its completely open position.

What I claim as new and desire to secure by Letters Patent is:
 1. A doorsafety latch comprising substantially arcuate lug means adapted to bemounted on a door, a substantially enlarged head mounted on the free endof said lug means, a base member adapted to be mounted on a walladjacent said lug means, yoke means having spaced apart leg portions,means pivotally mounting free ends of said leg portions to said basemember, a plurality of stepped surfaces mounted on said free end of oneof said leg portions, said leg portions being sufficiently spaced apartadjacent to said pivot means to permit said enlarged head to passtherethrough and the rest of said leg portions being only sufficientlyspaced apart to permit said lug means to slide therethrough and detentmeans mounted at said pivot means providing substantial resistance tothe pivotal movement of said yoke means, said detent means having a borein said base member in substantial alignment with said stepped surfaces,a substantially elongated detent member secured in said bore having afree end portion engaging said stepped surface, said detent memberhaving a substantially pointed free end portion and being reduced indiameter in proximity of its mid-portion permitting said detent memberto bend at said mid-portion to become foreshortened as said steppedsurfaces move past said detent member upon applying increased forces atsaid yoke means, said detent member engaging one of said steppedsurfaces upon the partial opening of said door.